Development of experiment and theory to detect and predict ligand phase separation on silver nanoparticles.

Zachary Farrell, Steve Merz, Jon Seager, Caroline Dunn, Sergei Egorov, David L Green

Index: Angew. Chem. Int. Ed. Engl. 54 , 6479-82, (2015)

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Abstract

MALDI mass-spectrometry measurements are combined with self-consistent mean-field (SCF) calculations to detect and predict ligand phase separation on Ag nanoparticles. The experimental and theoretical techniques complement each other by enabling quantification of the nearest-neighbor distribution of a ligand mixture in a monolayer shell. By tracking a characteristic metallic fragment family, analysis of a MALDI spectrum produces a frequency distribution corresponding to specific ligand patterning. Inherent to the SCF calculation is the enumeration of local interactions that dictate ligand assembly. Interweaving MALDI and SCF facilitates a comparison between the experimentally and theoretically derived frequency distributions as well as their deviation from a well-mixed state. Thus, we combine these techniques to detect and predict phase separation in monolayers that mix uniformly or experience varying degrees of de-mixing, including microphase separation and stripe formation. Definition of MALDI removed as this is a commonly recognized technique. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.